Seat assembly for use in fracturing subsurface geologic formations

ABSTRACT

An embodiment of a seat assembly cooperates with an isolation member to isolate a well first portion from a well second portion and comprises one of a recess or a chamber to receive an explosive charge. A pressure sensor, a circuit, and a battery may also be received into the same or other recess(es) or chamber(s) to trigger detonation, or a tool may be run into the well to engage and detonate the explosive charge. The seat assembly is secured in the well casing by at least one deployable gripping component and it resists deformation under the application of a substantial pressure differential across the seat and an isolation member sealably engaged therewith. Detonation of the explosive charge disables the at least one gripping component, thereby enabling retrieval of a body of the seat assembly to the surface using a tool coupled to a wireline or a coiled tubing string.

STATEMENT OF RELATED APPLICATIONS

This application depends from and claims priority to U.S. Provisional Application No. 62/556,922 filed on Sep. 11, 2017.

BACKGROUND Field of the Invention

The present invention relates to a seat assembly for use with an isolation member, such as a ball, to fluidically isolate a well casing first portion from a well casing second portion and to thereby expose a geologic formation in fluid communication with the well casing first portion to, while isolating geologic formations in fluid communication with the well casing second portion from, fluid pressure applied for hydraulically fracturing the geologic formation in fluid communication with the well casing first portion. Hydraulic fracturing operations performed using the seat assembly can enhance recovery and rates of production of hydrocarbons from a well that penetrates the fractured geologic formation.

Background of the Related Art

Hydraulic fracturing is the fracturing of oil-bearing rock using a pressurized liquid. Some hydraulic fractures form naturally. Induced hydraulic fracturing or hydro-fracturing, commonly known as “fracking,” is a technique in which a fluid, typically water, is mixed with a proppant and chemicals to form a mixture that is injected at high pressure into a well to create small fractures in a hydrocarbon-bearing geologic formation along which the hydrocarbon fluids such as gas, oil or condensate may migrate to the well for production to the surface. Hydraulic pressure is removed from the well, then small grains of the proppant, for example, sand or aluminum oxide, hold the fractures open once the formation pressure achieves an equilibrium. The technique is commonly used in wells for shale gas, tight gas, tight oil, coal seam gas and hard rock wells. This well stimulation technique is generally only conducted once in the life of the well and greatly enhances fluid removal rates and well productivity.

A hydraulic fracture is formed by pumping fracturing fluid into a perforated section of the well at a rate sufficient to increase pressure downhole at the target zone (determined by the location of the well casing perforations) to exceed that of the fracture gradient (pressure gradient) of the rock. The fracture gradient is defined as the pressure increase per unit of the depth due to its density and it is usually measured in pounds per square inch per foot or bars per meter. The rock cracks and the fracture fluid continues further into the rock, extending the crack still further, and so on. Fractures are localized because pressure drop off with frictional loss attributed to the distance from the well. Operators typically try to maintain “fracture width,” or slow its decline, following treatment by introducing into the injected fluid a proppant—a material such as grains of sand, ceramic beads or other particulates that prevent the fractures from closing when the injection is stopped and the pressure of the fluid is removed. The propped fracture is permeable enough to allow the flow of formation fluids to the well. Formation fluids include gas, oil, salt water and fluids introduced to the formation during completion of the well during fracturing.

The location of one or more fractures along the length of the borehole is strictly controlled by various methods that create or seal off holes in the side of the well. A well may be fracked in stages by setting an isolation member seat, such as a bridge seat, below the geologic formation to be fracked to isolate one or more lower geologic zones open to the well from the anticipated pressure to be later applied to a zone closer to the surface. An isolation member, such as a ball of a predetermined diameter and/or profile, is introduced into the well to engage the corresponding isolation member seat. When the isolation member engages the isolation member seat installed in the bore of the well casing, the isolation member seats in the isolation member seat to form a seal that isolates the well casing second portion below the seat from the hydraulic fracturing pressure to be imposed on a geologic formation in fluid communication with the well casing first portion of the casing having perforations above the seat. The hydraulic fracturing pressure is applied at the wellhead and fluidically communicated down the well casing.

Hydraulic-fracturing equipment used in oil and natural gas fields usually consists of a slurry blender, one or more high-pressure, high-volume fracturing pumps (typically powerful triplex or quintuplex pumps) and a monitoring unit. Associated equipment includes fracturing tanks, one or more units for storage and handling of proppant, high-pressure treating iron, a chemical additive unit (used to accurately monitor chemical addition), low-pressure flexible hoses, and many gauges and meters for flow rate, fluid density, and treating pressure. Chemical additives are typically 0.5% percent of the total fluid volume. Fracturing equipment operates over a range of pressures and injection rates, and can reach up to 100 megapascals (15,000 psi) and 265 litres per second (9.4 cu. ft./sec or 100 barrels per min.).

A problem that can be encountered in a fracking operation involves the impairment to subsequent operations that can result from the presence of the isolation member engaged with the isolation member seat. After the fracking operation is concluded, the surface pressure is restored to a pressure at which the well will flow and formation fluids flow to the wellhead at the surface for recovery. Conventional isolation member seats typically remain in the well casing. Conventional isolation member seats can restricts oil flow and/or obstruct subsequent well operations.

A workover operation can be implemented in which a drilling instrument is introduced into the well casing to drill out and to mechanically destroy the isolation member seat, but a workover operation requires that a workover rig be brought to the surface location of the well for downhole operations. The need for the rental, transportation, rigging up and use of a rig imposes substantial delays and substantial costs.

BRIEF SUMMARY

Seat assemblies for sealably receiving isolation members such as, for example, but not by way of limitation, balls pumped downhole from the surface into a well casing, can be secured in well casing at a predetermined position to cooperate with the isolation member received therein to isolate a well casing first portion from a well casing second portion. One type of seat assembly is secured in the well casing by radially outward expansion of one or more components of the seat assembly to engage the well casing in an interference fit. The expanded component of the seat assembly engages and grips the well casing to secure the seat assembly in position. Another type of seat assembly relies on one or more deployable gripping members such as, for example, but not by way of limitation, one or more deployable slips that can be moved from a run-in or retracted position to a deployed position to engage and grip the well casing.

An embodiment of the present invention provides a fracking isolation member seat assembly having one or more gripping components such as, for example, one or more deployable slips and one or more displacement members for engaging and deploying the one or more deployable slips, for securing the seat assembly in position in the well casing. The term “gripping components,” as that term is used herein, may include not just the one or more components of the seat assembly that are deployable to engage and bite into the well casing, but also the one or more components that engage and deploy or displace the one or more components that engage and bite into the well casing, components that provide support to the one or more components that engage and deploy or displace the one or more components that engage and bite into the well casing, and components that provide support to the one or more components that engage and bite into the well casing. It will be understood that the isolation member seat assembly can be released from its secured position within the well casing by disabling the one or more components that engage and deploy or displace the one or more components to engage and bite into the well casing. It will be further understood that the isolation member seat assembly can be released from its secured position that explosively compromising the body of the isolation member seat assembly into which the recesses are formed because, without the body having structural integrity, the components that engage and bite into the well casing (such as slips) and the components that engaging and displace the components that engage and bite into the well casing (such as the displacement members), have nothing to provide for reaction forces against the well casing. The one or more gripping components may be, but are not limited to, the body of the isolation member seat assembly, one or more slips of the isolation member seat assembly, and/or one or more slip displacement members that engage and then deploy one or more slips. The one or more gripping components can be disabled by detonation of a strategically placed explosive charge provided within the seat assembly such as, for example, within a chamber or a recess within a body of the seat assembly, or around the exterior of the body of the isolation member seat assembly, to produce, upon detonation of the explosive charge, displacement of or destruction of the one or more gripping components that secure the seat assembly in the well casing. The one or more gripping components of an embodiment of the seat assembly of the present invention may comprise a material that provides favorable hardness and favorable compressive strength for gripping a well casing or for engaging and displacing another component that grips the well casing, but one that subsequently shatters or fragments when exposed to the shock caused by detonation of an explosive charge disposed in close proximity thereto to disable the gripping component that grips the well casing. In one embodiment, the material is one that dissolves after exposure to well fluids due to the dramatically and substantially increased surface area resulting from the shattering or fragmentation caused by the explosive charge. In another embodiment, the body of the seat assembly may comprise a material that can be fragmented by detonation of an explosive charge and the fragments resulting therefrom may be of a material that is dissolvable in well fluids as a result of the dramatically increased surface area of the fragments as opposed to the limited surface area exposed prior to fragmentation. In this embodiment, as with other embodiments, the components of the seat assembly that are deployed to engage and bite into the well casing are not likely to comprise a dissolvable material since dissolvable materials are not optimal for forming teeth that effectively bite into steel well casing with the grip needed to withstand the large forces that will be imparted to the seat assembly and the isolation member received thereon during a fracturing operation.

An embodiment of the seat assembly of the present invention provides a fracking isolation member seat assembly having one or more gripping components such as, for example, one or more deployable slips and one or more displacement members for engaging and deploying the one or more deployable slips, for securing the seat assembly in position in the well casing. The term “gripping components,” as that term is used herein, may include not just the one or more components of the seat assembly that are deployable to engage and bite into the well casing, but may also be the one or more components that engage and deploy or displace the one or more components that engage and bite into the well casing. It will be understood that the seat assembly can be released from its secured position within the well casing by disabling the one or more components that engage and deploy or displace the one or more components to engage and bite into the well casing. The one or more gripping components may be, but are not limited to, one or more slips, and/or the one or more slip displacement members that engage and then deploy the one or more slips. The one or more gripping components can be disabled by detonation of a strategically placed explosive charge provided within the seat assembly such as, for example, within a chamber or a recess within a body of the seat assembly, or around the exterior of the body of the isolation member seat assembly, to produce, upon detonation of the explosive charge, displacement of or destruction of the one or more gripping components that secure the seat assembly in the well casing. The one or more gripping components of an embodiment of the seat assembly of the present invention may comprise a material that provides favorable hardness and favorable compressive strength for gripping a well casing or for engaging and displacing another component that grips the well casing, but one that subsequently shatters or fragments when exposed to the shock caused by detonation of an explosive charge disposed in close proximity thereto to disable the gripping component. In one embodiment, the material is one that dissolves after exposure to well fluids due to the dramatically and substantially increased surface area resulting from the shattering or fragmentation caused by the explosive charge. In another embodiment, the body of the seat assembly may comprise a material that can be fragmented by detonation of an explosive charge and the fragments resulting therefrom may be of a material that is dissolvable in well fluids as a result of the dramatically increased surface area of the fragments as opposed to the limited surface area exposed prior to fragmentation. In this embodiment, as with other embodiments, the components of the seat assembly that are deployed to engage and bite into the well casing are not likely to comprise a dissolvable material since dissolvable materials are not optimal for forming teeth that effectively bite into steel well casing with the grip needed to withstand the large forces that will be imparted to the seat assembly and the isolation member received thereon during a fracturing operation.

In one embodiment of the isolation member seat assembly of the present invention, one or more gripping components of the seat assembly such as, for example, one or more slips, can be movably disposed on a body of the seat assembly, the one or more gripping components movable from a run-in or retracted position proximal to, or within a recess or a chamber in, a body of the seat assembly to a deployed position distal to, or deployed from a recess or a chamber in, the body of the seat assembly. An explosive charge strategically positioned proximal to the one or more gripping components can be detonated after the geologic formation fracturing operation to disable the one or more gripping components so that the isolation member seat assembly can be removed from its position within the well casing and retrieved to the surface using a tool run on a wireline or a coiled tubing string. “Disabling,” as that term is used herein, includes destroying, shattering, damaging, displacing, dislodging, compromising and/or fragmenting the one or more gripping components.

In one embodiment of the isolation member seat assembly, one or more gripping components of the seat assembly such as, for example, one or more slips, can be movably disposed on, or within a recess or chamber of, the body of the seat assembly, the one or more slips movable from a run-in position to a deployed position, and a displacement member can be disposed adjacent to the one or more slips, the displacement member movable from a retracted position to an engaged position to engage and displace the one or more gripping components from the run-in position to the deployed position to engage and grip the well casing and to thereby secure the seat assembly in a position within the well casing. An explosive charge is strategically positioned on, or within a chamber or recess of, the body of the seat assembly and proximal to one of the one or more gripping components. For example, but not by way of limitation, the explosive charge may be positioned on, or within a chamber or recess of, the body of the seat assembly and proximal to at least one of a displacement member and a slip that can be engaged by and deployed to a gripping position by movement of the displacement member. The explosive charge can be detonated after the fracturing operation to disable at least one of the displacement member and the one or more slips so that the isolation member seat assembly can be subsequently removed from its position within the well casing using, for example, a tool run on a wireline or a coiled tubing string. In one embodiment, the explosive charge can be disposed within a chamber of the body of the seating assembly that is sealed to prevent unwanted contamination by or exposure to well fluids wherein the chamber of the body is proximal to at least one of the displacement member in the engaged position and the one or more slips in the deployed position so that upon detonation of the explosive charge at least one of the displacement member and the one or more slips are disabled and the seat assembly is thereby released from its secured position within the well casing.

In one embodiment of the isolation member seat assembly of the present invention, a battery, a pressure sensor and a circuit are included on, or within a chamber or a recess of, the body of the seat assembly along with the explosive charge. The pressure sensor is disposed in fluid communication with fluid in the well casing and detects a predetermined pressure threshold or, alternately, a pressure drop, or both in sequence. The pressure sensor may optionally, upon sensing the pressure threshold, pressure drop or sequence of both, initiate a predetermined timer delay period prior to sending a detonation signal or charge from the battery to the explosive charge to detonate the explosive charge, or it may generate and send the detonation signal or charge upon detecting the pressure threshold, pressure drop or sequence of both. For the embodiment of the seat assembly wherein the pressure sensor initiates a predetermined time delay after detecting the pressure threshold or pressure drop, upon elapse of the predetermined timer delay period, a circuit is completed that delivers an electrical current from the battery to the explosive charge to detonate the explosive charge and to thereby disable one or more of the gripping components of the isolation member seat assembly that secure the seat assembly in a position within the well casing. For the pressure subsidence-triggered embodiment, upon subsidence of the pressure in the well casing at the seat assembly to a predetermined pressure that is less than the higher threshold pressure that initiates the detonation process by arming the circuit, a circuit is completed that delivers an electrical current from the battery to the one or more explosive charges to detonate the one or more explosive charges and to thereby disable the one or more gripping components of the seat assembly that secure the seat assembly in the well casing.

In another embodiment of the isolation member seat assembly of the present invention, the seat assembly includes the one or more explosive charges for disabling the gripping components that secure the seat assembly in a position in the well casing. For example, one embodiment includes gripping components comprising a displacement member that is movable on the body of the seat assembly from a run-in position to an engaged position. The run-in position of the displacement member is the position in which an adjacent one or more slips are left in a run-in or retracted position, and the engaged position of the displacement member is the position in which the displacement member engages and displaces the adjacent one or more slips from the run-in or retracted position to the deployed position. In one embodiment of the seat assembly, the seat assembly does not include a battery, a pressure sensor or a circuit. Instead, the electrical charge required for detonating the one or more explosive charges and thereby disabling the one or more gripping components of the seat assembly is provided by way of a wireline unit, a coiled tubing string or some other tool for being run into a well to the isolation seat assembly. The explosive charge is, in this embodiment, protected against inadvertent detonation due to, for example, a malfunction in or failure of the pressure sensor or the circuit. The isolation member seat assembly that includes the one or more explosive charges may also include electrical leads coupled at a first end to the one or more explosive charges and having a second end disposed in a position on the isolation member seat assembly to engage a tool that is lowered into the well casing from the surface to electrically detonate the one or more explosive charges and to thereby disable one or more gripping components of the isolation member seat assembly. For example, the electrical leads may terminate at one or more electrical contacts disposed in a position adjacent to a seat of the seat assembly that is sealably engaged by the isolation member during the fracking operation, the seat being disposed at a proximal end of the isolation member seat assembly. A tool having one or more electrical contacts may be disposed into engagement with the seat assembly after the fracking operation, and the one or more contacts on the tool that is run into the well to engage the seat assembly may be positioned on the tool at a predetermined position and/or spacing, and the contacts may be positioned, spaced and/or sized for engagement with corresponding electrical contacts on the seat assembly so that an electrical charge can be delivered from the tool that is run into the well casing through the engaged contacts and to the one or more explosive charges to thereby detonate the one or more explosive charges and thereby disable the one or more gripping components that secure the isolation member seat assembly in the well casing prior to detonation of the one or more explosive charges.

The unobstructed well casing obtainable by use of embodiments of the fracking isolation member seat assembly of the present invention, along with the lack of obstruction of subsequent well operations, increases the success and effectiveness of the fracking process, lowers or eliminates workover rig rental costs, prevents unwanted delays in subsequent well operations after the fracking process, and gets oil to market faster and with less expense.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an elevation view of a top portion of an embodiment of an isolation member seat assembly of the present invention having a top body and a pair of distally extending legs.

FIG. 2 is a plan view of a bottom portion of an embodiment of an isolation member seat assembly of the present invention that is adapted for coupling with the top portion of FIG. 1.

FIG. 3 is a sectional elevation view of a bottom portion of an embodiment of an isolation member seat assembly of the present invention showing a pair of recesses in the body of the bottom portion, each recess having a slip in a retracted or run-in position, a displacement member in the run-in configuration, and a small explosive charge adjacent to the each displacement member.

FIG. 4 an elevation view of the bottom portion of FIG. 3 aligned with the top portion of FIG. 1 for receiving the legs of the top portion into the channels of the bottom portion of the embodiment of the isolation member seat assembly of the present invention.

FIG. 5 is the view of the embodiment of the seat assembly of FIG. 4 after the legs of the top portion have been inserted into the channels of the bottom portion until the distal ends of the legs engage the corresponding displacement member disposed within each of the recesses.

FIG. 6 is the view of the embodiment of the seat assembly of FIG. 5 after the legs of the top portion have been fully inserted into the channels of the bottom portion to displace each of the displacement members from the run-in position to the engaged position against the slips to displace the slips from the run-in or retracted position to the deployed position to engage and grip the well casing and to secure the seat assembly in a position within the well casing. This configuration enables the seat assembly to receive and sealably cooperate with an isolation member such as, for example, a ball or a plug, to isolate a portion of the well casing below the deployed isolation member seat assembly from a portion of the well casing above the deployed isolation member seat assembly.

FIG. 6A is an enlarged view of a portion of a leg of the top portion as it engages a portion of a channel of the bottom portion of the isolation member seat assembly of the present invention.

FIG. 7 is a modification of the embodiment of the seat assembly of FIG. 6 having a pair of conductive leads, each having a proximal end coupled to a contact on the bore of the bottom portion of the seat assembly and a distal end coupled to the explosive charge disposed adjacent to each of the displacement members in each of the recesses in the body of the bottom portion of the isolation member seat assembly.

FIG. 8 is a tool for being inserted into the deployed isolation member seat assembly, engaging the contacts, and for delivering an electrical current to the contacts to detonate the explosive charges and to thereby disable each of the displacement members and/or the slip of each recess to enable retrieval of the isolation member seat assembly from the well casing.

FIG. 9 is a view of one embodiment of the seat assembly of the present invention after the explosive charges are detonated to disable the gripping components by shattering a frangible gripping component to release the isolation member seat assembly from a secured position within the well casing.

FIG. 10 is a view of a tool being positioned within a bore of the isolation member seat assembly after it has been explosively disabled and released from a secured position within the well casing so that the released seat assembly can be retrieved and removed from the well casing.

DETAILED DESCRIPTION

The embodiment of the isolation member seat assembly contains one or more explosive charges that can be detonated to disable one or more gripping components of the isolation member seat assembly that are deployed to secure the seat assembly in the well casing. Once the isolation member seat assembly is movable within the well casing, it can be retrieved to the surface and removed from the well casing to prevent unwanted obstructions.

It will be understood that the seat of the isolation member seat assembly may have a variety of exterior shapes that can be adapted to engage and seal with a correspondingly shaped isolation member such as, for example, but not by way of limitation, a ball or a dart. Although, the appended drawings illustrate an apparatus of the present invention having a seat for engaging a spherical sector of a spherical isolation member, the appended drawings merely illustrate a function that can be provided by other isolation members with alternate exterior shapes and configurations for engaging a correspondingly shaped seat of an isolation member seat assembly. The appended drawings are merely for illustration and should not be considered as limiting of the invention and other shapes, such as, for example, wedges, cones or cylinders, can also be employed for establishing a seal.

In one embodiment, the gripping components of the isolation member seat assembly that are deployed to secure the isolation member seat assembly in the well casing. The gripping components can be made of a composite material whereby the gripping components, such as, for example, but not by way of limitation, slips or displacement members to engage and displace the slips, are dislodged and/or fragmented by an explosive charge directed at the slips and/or the displacement members. The isolation member seat assembly can then be retrieved to the surface of the well with a fishing tool thereby clearing the well of any unwanted obstruction. Gripping components, that that terms is used herein, may refer to slips, displacement members to engage and displace the slips, or both, or to other components that can be used to effect the securing of the isolation member seat assembly in the well casing.

One embodiment of the isolation member seat assembly comprises a body having one or more recesses, apertures or holes into or through which components, such as, for example, a safety fuse, a pressure sensor, an explosive charge, a battery, and a timer circuit may be inserted. It will be understood that an embodiment of an isolation member seat assembly may have other configurations and may also be assembled from mating components to form a closed chamber to contain the components.

Embodiments of an isolation member seat assembly of the present invention may further include a timer-controlled detonator. The pressure sensor may be provided to generate a signal that enables or initiates the electrical circuit that delivers a detonating current flow from a battery to the one or more explosive charges. The provision of the pressure sensor to complete and thereby enable the detonation circuit causes the pressure sensor to function as a safety fuse without which the explosive charge would not be detonated and the isolation member seat assembly would be unable to self-release.

In one embodiment, the dissolvable components of embodiments of the apparatus may comprise one of many magnesium and aluminum compositions. For example, but not by way of limitation, in embodiments of the isolation member seat assembly of the present invention in which the body of the isolation member seat assembly is explosively disabled to release the isolation member seat assembly from a fixed position within the well casing, the body may comprise one or both of magnesium and aluminum, or some other material that will dissolve in certain well fluids so that debris can be eliminated from the well and fragmented or shattered components of the isolation member seat assembly will not present unwanted obstructions for other tools and downhole devices.

FIG. 1 is an elevation view of a top portion 10 of an isolation member seat assembly of an embodiment of the present invention having a top body 18 with a shaped seat 16 therein for receiving and sealably engaging an isolation member (not shown) such as, for example, a spherical ball, and for sealably engaging a spherical sector thereof. The top portion 10 further includes a proximal end 17, a distal end 19, a bore 14 through the top body 18 and a pair of distally extending legs 12. Each leg 12 has a distal end 13, a proximal end 11 and a plurality of teeth 15 therebetween. Each leg 12 of the top portion 10 of the embodiment of the isolation member seat assembly of FIG. 1 has a length 12A.

FIG. 2 is a plan view of a bottom portion 20 of an embodiment of an isolation member seat assembly of the present invention that is adapted for cooperating with and for coupling with the top portion 10 of FIG. 1. The bottom portion 20 includes a body 21, a bore 25, a pair of channels 22, an exterior wall 28, and a proximal end 26. Each of the channels 22 include an entry end 23 and a plurality of teeth (not shown in FIG. 2) and the channels 22 and the entry ends 23 thereof are spaced apart, one from the other, to correspond to the separation distance between the legs 12 extending from the top body 18 shown in FIG. 1.

FIG. 3 is a sectional elevation of the bottom portion 20 of the embodiment of an isolation member seat assembly of the present invention of FIG. 2 showing a pair of recesses 30 in the body 28 of the bottom portion 20, each recess 30 having a movable slip 41 disposed in a retracted or run-in position, a movable displacement member 31 disposed adjacent to the movable slip 41, the displacement members 31 also in the run-in position, and a small explosive charge 40 adjacent to the displacement member 31 in each recess 30. Each slip 41 has gripping teeth 42 and a sloped surface 43 for slidably engaging a sloped surface 32 on the adjacent displacement member 31. Each slip 41 is coupled to the body 28 of the bottom portion 20 by a spring element 52 that accommodates movement of the slip 41 from the run-in or retracted position to the deployed position (not shown in FIG. 3—see FIG. 6). Each displacement member 31 includes a notch 34 for receiving a distal end 13 of a leg 12 of the top portion 10 of the isolation member seat assembly 100. The bore 25 of the bottom portion 20 aligns with the bore 14 of the top portion 10 when the legs 12 of the top portion 10 are aligned with the channels 22 of the bottom portion 20, as shown in FIG. 4 and discussed below.

FIG. 4 an elevation view of the bottom portion 20 of FIG. 3 aligned with the top portion 10 of FIG. 1 for receiving the legs 12 of the top portion 10 into the channels 22 of the bottom portion 20 of the embodiment of the isolation member seat assembly 100 of the present invention. The distal ends 13 of the legs 12 of the top portion 10 are positioned for being received into and inserted into the openings 23 of the channels 22 of the bottom portion 20. The teeth 15 of the legs 12 are the same in shape and number per inch (or cm.) of legs 12 as the teeth 29 within the channels 22 and the legs 12 and channels 22 together acts as linear ratchets as the legs 12 are inserted into the channels 22 that allow adduction (movement of one towards the other) of the top portion 10 and the bottom portion 20 but to thereafter oppose abduction (movement of one away from the other) of the top portion 10 and the bottom portion 20.

FIG. 5 is the view of the embodiment of the seat assembly 100 of FIG. 4 after the distal ends 13 of the legs 12 of the top portion 10 have been inserted into the openings 23 of the channels 22 of the bottom portion 20 until the distal ends 13 of each of the legs 12 engages a notch 34 in the displacement member 31 disposed within the corresponding recess 30. The displacement member 31 remains in its original position until the legs 12 extending from the top portion 10 are inserted further into the channels 22. It can be seen in FIG. 5 that there is a uninserted portion 26 of each of the legs 12 that have yet to enter the opening 23 of the corresponding channel 22.

Also shown in FIG. 5 is a setting tool 70 having a motor 72 for rotating a threaded shaft 74. The threaded shaft 74 is threadedly engaged with a sacrificial retainer 76 that engages the bottom portion 20 of the seat assembly and the setting tool 70 includes a stop 78 that engages the top portion 10 of the seat assembly 100. Power, in the form of, for example, hydraulic power provided through a coiled tubing string or electrical current provided through a conductive wireline, is provided to the motor 72 through power supply conduit 80. Rotation of the threaded shaft 74 by operation of the motor 72 as shown by arrow 81 causes the sacrificial retainer 76 to be drawn upwardly and against the bottom portion 20 as to displace the bottom portion 20 against the stop 78 to force the legs 12 of the top portion 10 further into the channels 22 of the bottom portion 20. As the legs 12 are forced further into the channels 22 by rotation of the threaded shaft 74, the distal ends 13 of the legs 12 displace the displacement member 31 from the run-in position shown in FIG. 5 and against the slip 41 to displace the slip 41 from the run-in or retracted position shown in FIG. 5 to a deployed position shown in FIG. 6. The explosive charge 40 may, in one embodiment, move with the displacement member 31 or, in another embodiment, it may remain in place as the displacement member 31 moves downwardly to displace the slip 41 radially outwardly in the direction shown by the arrows 77 in FIG. 6.

FIG. 6 is the view of the embodiment of the seat assembly 100 of FIG. 5 after the threaded shaft 74 is rotated further to displace the legs 12 of the top portion 10 further into the channels 22 of the bottom portion 20 to displace the displacement member 31 from the run-in position (shown in FIG. 5) to the engaged position against the slips 41 to displace the slips 41 radially outwardly in the direction of arrows 77 from the run-in or retracted position to the deployed position to engage the teeth 42 and “bite” or grip the well casing 88 and to secure the seat assembly 100 in a position within the well casing 88. This configuration enables the seat assembly 100 to receive and cooperate with an isolation member (not shown) such as, for example, a ball or a plug, that is introduced into the well casing 88 and pumped down the well casing 88 to sealably engage the seat assembly 100 and to thereby isolate a distal portion 88B of the well casing 88 below the seat assembly 100 from a proximal portion 88A of the well casing 88 above the seat assembly 100. Continued rotation of the threaded shaft 74 causes the sacrificial retainer 76 to fail and deform or collapse the arms 73 of the sacrificial retainer 76 downwardly in the direction of arrows 79 so that the setting tool 70 can be pulled away from the seat assembly 100 and out of the well casing 88 to clear the well casing 88 for introduction of the isolation member (not shown) to engage the now-secured seat assembly 100.

FIG. 6A is an enlarged view of a portion of a leg 12 of the top portion 10 as it engages a portion of a channel 22 of the bottom portion 20 of the isolation member seat assembly of the present invention. It can be seen how the leg 12 and the channel 22 together form a linear ratchet that prevents the top portion 10 (not shown except for leg 12) from backing away from the bottom portion 20.

FIG. 7 is a modification of the embodiment of the isolation member seat assembly of FIG. 6 having a plurality of conductive leads 83, each having a proximal end 84 coupled to a contact 82 on or within the bore 25 of the bottom portion 20 of the isolation member seat assembly 100 and a distal end 86 coupled to the explosive charge 40 disposed adjacent to the displacement member 31 in each recess 30 in the bottom portion 20. It will be understood that the contacts 82 may be positioned at locations on the isolation member seat assembly 100 other than that shown in FIG. 7 such as, for example, at the proximal end 17 of the top portion 10 or on the seat 16 that sealably engages the isolation member (not shown).

FIG. 8 is an embodiment of a detonation tool 181 for being inserted into the seat assembly 100 of FIG. 7, for therein engaging the contacts 82 shown in FIG. 7, and for delivering an electrical current to the contacts 82 to detonate the explosive charges 40 and to thereby disable at least one gripping component (for example, but not by way of limitation, the displacement member 31 and/or the slip 41) of each recess 30 to render the isolation member seat assembly 100 unsecured in the well casing 88 and to thereby enable retrieval of the seat assembly 100 from the well casing 88. It will be understood that detonation tools of other configurations may be adapted for engaging contacts 82 that are positioned at other locations on the isolation member seat assembly 100 as discussed in relation to FIG. 7 above. The detonation tool 181 of FIG. 8 includes a connector 191 for connecting the detonation tool 181 to a wireline 184 that provides electrical current to the detonation tool electrical leads 183 that terminate at tool contacts 182 on the exterior 192 of the detonation tool 181. The detonation tool 181 further includes a tool shoulder 180 that engages with isolation member seat assembly shoulder 89 within the bore 25 of the bottom portion 20 of the isolation member seat assembly 100 (see FIG. 7). The tool shoulder 180 of the tool 181 of FIG. 8 is strategically spaced axially from the tool contacts 182 the same as the seat assembly shoulder 89 is spaced from the isolation member seat assembly contacts 82 in FIG. 7 so that inserting the detonation tool 181 into the isolation member seat assembly 100 until the tool shoulder 180 engages the isolation member seat assembly shoulder 89 ensures that the tool contacts 182 will be in electrical engagement with the isolation member seat assembly contacts 82. An electrical current or signal is delivered through the wireline 184 and through the detonation tool electrical leads 183 and detonation tool contacts 182 to the isolation member seat assembly contacts 82, and from the isolation member seat assembly contacts 82 through the electrical leads 83 (see FIG. 7) to the electrical charges 40 to initiate detonation and disablement of the at least one of the gripping components (for example, the displacement member 31 and/or the slips 41) or any other gripping components that are used to secure the isolation member seat assembly 100 within the well casing 88. In other embodiments of the detonation tool 181, an electrical current or signal can be delivered by a detonation tool 181 coupled to a coiled tubing string by use of a small, hydraulically powered generator to harness hydraulic fluid flow provided through the coiled tubing string to generate an electrical signal to detonate the explosive charges 40 of the isolation member seat assembly 100.

It will be understood that the use of a detonation tool 181 to engage and deliver an electrical current to detonate the explosive charge 40 of an isolation member seat assembly 100 offers flexibility and cost savings by enabling an operator to run the detonation tool 181 into a well casing 88 and to detonate the explosive charge 40 after each stage of a fracturing operation. The isolation member seat assembly 100 released by the detonation can be left in the well casing 88 while subsequent stages of the fracturing operation commence uphole, resulting in additional isolation member seat assemblies 100 being secured in the well casing 88, used for the fracturing of a stage, then engaged by the detonation tool 181 to detonate the explosive charge(s) 40 to release the isolation member seat assembly 100 which is also left in the well casing 88. This approach allows multiple released isolation member seat assemblies 100 to be harvested from the well casing 88 in a single trip using a retrieval tool adapted for retrieving the released seat assemblies 100, as will be discussed in more detail below in relation to FIG. 10.

FIG. 9 is a view of one embodiment of the isolation member seat assembly 100 of the present invention after an explosive charge(s) 40 (not shown in unitary form—is shown in fragmented form as it has been destroyed when the explosive 40 was detonated) is detonated to disable the gripping components, for example, the displacement members 31 and/or the slips 41 displaced thereby, by shattering a frangible displacement member 31A (now shown in FIG. 9 in a shattered or fragmented state) to disable the gripping components and to thereby release the isolation member seat assembly 100 from a secured position within the well casing 88. The fragmented displacement member 31A of this embodiment may be of a material having favorable compression resistance for transferring force applied by the distal end 13 of the leg 12 of the top portion 10 through the displacement member 31 and for using that displacement member 31 for engaging and displacing an adjacent one or more slips 41 from a run-in or retracted position (see FIG. 5) to a deployed position (see FIG. 6) to engage and grip the well casing 88, but also of a material that is also frangible so as to shatter (as shown by shattered displacement member 31A in FIG. 9) or to fragment upon exposure to the shock of an explosive charge 40 (not shown in FIG. 9—see FIG. 6) detonated in close proximity to the displacement member 31A. It will be understood that many materials such as, for example, but not by way of limitation, grey cast iron or ceramics, may provide excellent resistance to deformation in a compressive mode, as in when the gripping components (displacement member 31 and/or slips 41) are deployed, but may also advantageously shatter and/or fragment into small pieces as shown by fragmented displacement member 31A upon and as a result of exposure to the shock of an explosive charge 40 (not shown in FIG. 9) detonation occurring in close proximity to the gripping components.

FIG. 9 also illustrates a retriever tool 36 having a stem 27 and a spring-biased arms 24 thereon. The retriever tool 36 may be run on, for example, a wireline or a coiled tubing string (not shown). The arms 24 are spring biased outwardly in the direction shown by arrows 33 away from the stem 27 by a spring element 35. The retriever tool 36 can be pushed in the direction of arrow 37 and the arms 24 will resiliently swing inwardly towards the stem 27 and against the spring elements 35 as they move through the bore 25 of the isolation member seat assembly 100, but will be restored to swing outwardly and away from the stem 27 once the arms 24 exit the bore 25 as the retriever tool 36 continues to move in the direction of arrow 37.

FIG. 10 is a view of the retriever tool 36 of FIG. 9 after being positioned further within a bore 25 of the isolation member seat assembly 100 after the isolation member seat assembly 100 has been explosively released from a secured position within the well casing 88 so that the released isolation member seat assembly 100 can be removed from the well casing 88. The retriever tool 36 comprises a spring-biased pair of arms 24 thereon that are pivotable by operation of a spring element 35 from an inwardly collapsed mode proximal to the stem 27 to an outwardly extended mode distal to the stem 27. It will be understood that retrieval of the tool 36 from the well casing 88 after the arms 24 move to the outwardly extended position shown in FIG. 10 will retrieve the released seat assembly 100 along with the tool 36 so that the seat assembly 100 can be removed from the well casing 88, excepting those pieces of the gripping components, such as the shattered displacement member 31A, that may be detached, displaced from and/or separated from the isolation member seat assembly 100. It will be understood that the retriever tool 36 can be adapted for retrieval of multiple released isolation member seat assemblies 100 from a single well casing 88 as discussed above in relation to FIG. 8.

It will be further understood that while the embodiment of the setting tool 70 with the threaded shaft and the sacrificial retainer arms used to set or deploy the gripping components of the isolation member seat assembly is illustrated herein at FIG. 5 with two, opposed sacrificially failing retainer arms, other embodiments may have three or more retainer arms or only one retainer arm. It will be further understood that while the embodiment of the retrieval tool 36 with the spring-biased arms used to retrieve the retrieval tool 36 and the isolation member seat assembly 100 after the gripping components (displacement member 31 and/or slips 41) are disabled by detonation of the explosive charge is illustrated herein with two, opposed spring biased arms, other embodiments may have three or more retainer arms or only one retainer arm.

It will be understood that other various tools can be used to deploy the gripping components of the seat assembly of the present invention and/or to retrieve the released isolation member seat assembly from the well casing without departure from the spirit and scope of the present invention, which is defined by the claims appended hereto. It will be understood that other various tools may be used to retrieve the released isolation member seat assembly from the well casing without departure from the spirit and scope of the present invention, which is defined by the claims appended hereto.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, components and/or groups, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The terms “preferably,” “preferred,” “prefer,” “optionally,” “may,” and similar terms are used to indicate that an item, condition or step being referred to is an optional (not required) feature of the invention.

The corresponding structures, materials, acts, and equivalents of all means or steps plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but it is not intended to be exhaustive or limited to the invention in the form disclosed.

Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. 

What is claimed is:
 1. An isolation member seat assembly, for sealably receiving an isolation member, securable in a set position in a well casing in a well to isolate a pressure within a well first portion from a pressure in a well second portion, the isolation member seat comprising: a body having a proximal end, a bore therethrough and at least one of a chamber and a recess within the body; at least one gripping component coupled to the body and movable from a retracted position to a deployed position to engage the well casing and to secure the body in the well casing; a seat at the proximal end of the body to sealably engage the isolation member; a battery received within the at least one of a chamber and a recess of the body; an explosive charge including an explosive material received within the at least one of a chamber and a recess of the body; a pressure sensor received within the at least one of a chamber and a recess of the body, the pressure sensor disposed in fluid communication an exterior surface of the body and adapted to generate a signal upon sensing a predetermined pressure; and a circuit received within the at least one of a chamber and a recess of the body, the circuit conductively coupled to receive a signal from the pressure sensor and to generate a current to the explosive charge in response thereto; wherein detonation of the explosive charge disables at least one of the at least one gripping member and the at least one displacement member to release the body from the secured position within the well casing.
 2. The isolation member seat assembly of claim 1, wherein the at least one gripping component comprises at least one slip coupled to the body of the seat assembly, the at least one slip movable from a retracted position to a deployed position.
 3. The isolation member seat assembly of claim 2, wherein the at least one gripping component further comprises at least one displacement member coupled to the body adjacent to at least one slip, the at least one displacement member movable from a run-in position to an engaged position to engage and displace the at least one adjacent slip from the retracted position to the deployed position and to thereby secure the seating assembly in a position at a targeted position in the well casing.
 4. The isolation member seat assembly of claim 1, wherein the at least one gripping component comprises a plurality of gripping components coupled to the body of the seat assembly and angularly spaced about an axis of the seat assembly.
 5. An isolation member seat assembly, for sealably receiving an isolation member, securable in a set position in a well casing in a well to isolate a pressure within a well first portion from a pressure in a well second portion, the isolation member seat comprising: a body having a proximal end, a bore therethrough and at least one of a chamber and a recess within the body; at least one gripping component coupled to the body and movable from a retracted position to a deployed position to engage the well casing and to secure the body in the well casing; at least one explosive charge disposed in one of a chamber and a recess in the body proximal to the at least one gripping component; a seat at the proximal end of the body to sealably engage the isolation member; and at least one conductive lead coupled at a distal end to the at least one explosive charge and at a proximal end to at least one contact secured to the body; wherein detonation of the at least one explosive charge disables the at least one slip to release the seat assembly from a secured position within the well casing; and wherein the contact is disposed in a position on the body for engagement by a tool positioned within the well casing to engage the seat assembly.
 6. The isolation member seat assembly of claim 5, wherein the tool is positionable within the well casing using one of a wireline and a coiled tubing string.
 7. The isolation member seat assembly of claim 5, wherein the tool engages the contact and introduces an electrical current through the at least one contact and the at least one conductive lead to the explosive charge to detonate the at least one explosive charge.
 8. The isolation member seat assembly of claim 5, wherein the at least one gripping component comprises two or more gripping components angularly spaced about the axis of the seat assembly.
 9. The isolation member seat assembly of claim 5, wherein the at least one gripping component of the seat assembly comprises at least one slip movable from a retracted position to a deployed position to engage and grip the well casing and to thereby secure the seat assembly in a targeted position within the well casing.
 10. The isolation member seat assembly of claim 9, wherein the eat least one gripping component of the seat assembly comprises at least one displacement member disposed adjacent to the at least one slip, the at least one displacement member coupled to the body of the seat assembly and movable from a run-in position to an engaged position to engage and deploy the at least one slip to the deployed position.
 11. The isolation member seat assembly of claim 5, wherein the at least one gripping component comprises a plurality of gripping components, each angularly spaced from the others about an axis of the seat assembly.
 12. The isolation member seat assembly of claim 11, wherein each of the plurality of gripping components comprise at least one slip coupled to the body of the seat assembly and movable from a retracted position to a deployed position to engage and grip the well casing and to thereby secure the seat assembly in the targeted position in the well casing.
 13. The isolation member seat assembly of claim 12, wherein each of the plurality of gripping components further comprises a displacement member movable coupled to the body of the seat assembly adjacent to each of the at least one slips of each gripping component, each displacement member movable from a run-in position to an engaged position to displace the at least one slip from the retracted position to a deployed position to engage and grip the well casing.
 14. A method of retrieving a seat assembly from a secured position in a well casing, comprising: providing one or more explosive charges coupled to the seat assembly; securing the seat assembly in the well casing at a targeted position by moving one or more gripping components coupled to the seat assembly from a retracted position to a deployed position to engage and grip the well casing; introducing an isolation member into the well casing; sealably engaging the isolation member with the secured seat assembly to isolate a well first portion above the seat assembly from a well second portion below the seat assembly; applying a substantial pressure to the well first portion to fracture one or more subsurface geologic formations in fluid communication therewith; detonating the one or more explosive charges to disable the one or more gripping components; and retrieving at least a body of the seat assembly from the well casing using a tool.
 15. The method of claim 14, wherein the one or more gripping components each comprises a slip coupled to the body of the seat assembly and movable from a retracted position to a deployed position to engage and grip the well casing.
 16. The method of claim 15, wherein the one or more gripping components each further comprises a displacement member coupled to the body of the seat assembly and movable from a run-in position to an engaged position to displace the slip from the retracted position to the deployed position.
 17. The method of claim 14, wherein the one or more gripping components comprises a plurality of gripping components, each angularly spaced one from the others about an axis of the seat assembly.
 18. The method of claim 14, wherein the step of detonating the one or more explosive charges to disable the one or more gripping components comprises: providing a pressure sensor, a circuit and a battery each within one of a chamber and a recess in the body of the seat assembly; connecting the pressure sensor, the battery, the one or more explosive charges and the circuit to enable delivery of an electrical current from the battery to the one or more explosive charges upon detection of a predetermined pressure signal using the pressure sensor; generating the predetermined pressure signal by applying the substantial pressure to the well first portion; sensing, with the pressure sensor, the predetermined pressure signal; and generating an electrical current from the battery to the one or more explosive charges to detonate the one or more explosive charges.
 19. The method of claim 14, wherein the step of detonating the one or more explosive charges to disable the one or more gripping components comprises: providing one or more conductive leads, each having a first end coupled to at least one of the one or more explosive charges and a second end coupled to one or more contacts provided on the seat assembly; introducing a tool into the well first portion having one or more contacts thereon for engaging the one or more contacts on the seat assembly; engaging the one or more contacts on the tool with the one or more contacts on the seat assembly; and delivering an electrical current to through the one or more contacts on the tool, the one or more contacts on the seat assembly, and the one or more conductive leads of the seat assembly to the one or more explosive charges to detonate the one or more explosive charges and to thereby disable the one or more gripping components.
 20. The method of claim 19, wherein the tool comprises one of: a wireline unit having an elongate conductive member therein for conducting an electrical current; and a coiled tubing string having a fluid powered electrical current generator coupled to a distal end of the coiled tubing string. 